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new e84f3975 RNG-191: Update PHILOX_4X64 performance results.
e84f3975 is described below
commit e84f39756f0f88302ca98f7c86450dd903029b6f
Author: Alex Herbert <[email protected]>
AuthorDate: Mon Mar 9 11:07:48 2026 +0000
RNG-191: Update PHILOX_4X64 performance results.
---
src/site/apt/userguide/rng.apt | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/site/apt/userguide/rng.apt b/src/site/apt/userguide/rng.apt
index 98903f0e..d974eba1 100644
--- a/src/site/apt/userguide/rng.apt
+++ b/src/site/apt/userguide/rng.apt
@@ -966,7 +966,7 @@ double[] coordinate = sampler.sample();
*-----------------------+---------:---------:---------:---------:---------:
| PHILOX_4X32 | 1.08214 | 0.57003 | 0.40638 | 0.39130 | 0.33465 |
*-----------------------+---------:---------:---------:---------:---------:
-| PHILOX_4X64 | 1.33244 | 0.56303 | 0.57400 | 0.64138 | 0.60899 |
+| PHILOX_4X64 | 1.45384 | 0.14840 | 0.13167 | 0.17748 | 0.15659 |
*-----------------------+---------:---------:---------:---------:---------:
@@ -975,6 +975,8 @@ double[] coordinate = sampler.sample();
The <<<RandomSource.JDK>>> generator uses thread-safe (synchronized)
<<<int>>> generation which has a performance overhead (see the <<<int>>>
generation results). Note that the output will be low quality and this
generator should not be used. See the {{{a5._Quality}Quality}} section for
details. Multi-threaded applications should use a generator for each thread.
The speed of <<<boolean>>> generation is related to the base implementation
that caches the 32-bit or 64-bit output from the generator. In these results
the 32-bit generators have the better performance. These timings are relative
and all implements are very fast. A RNG to compute boolean samples should be
chosen based on the {{{a5._Quality}quality}} of the output.
+
+ The <<<RandomSource.PHILOX_4X64>>> generator uses multiply high methods from
<<<java.lang.Math>>> if available. The <<<multiplyHigh>>> (JDK 9+) and
<<<unsignedMultiplyHigh>>> (JDK 18+) significantly increase performance if the
128-bit product of two 64-bit factors is supported by hardware instructions.
These results are on a platform with supported hardware.
* 4.2 Generating Gaussian samples
